Wide bandwidth sensing of micro angular motion

Abstract

There has been an increasing interest in sensing angular micro motion, ranging from personal tremor in the medical applications to sensitive vibration platform for surveillance in the defense applications. Sensing micro angular motion is a challenging task though because of the requirement of high accuracy. In addition, the motion is small which results in weak sensor signals. Hence, this paper proposes a method to sense micro angular motions. Inertial sensors, like accelerometers and gyroscopes, are small in size and is a great choice for several applications. Inertial Measurement Unit (IMU) is a strong candidate for high frequency motion because of the high velocity and acceleration, and hence strong signal strength. However, the drawbacks of accelerometer and gyroscope are drift and failure to sense micro motion under low frequency due to the low signal strength at lower frequency. Camera, on the other hand, is capable of sensing low frequency micro motion. Hence, to address the issue on drift, Weighted Fourier Linear Combiner (WFLC) is used to perform zero phase filter plus estimate the displacement. To increase the accuracy, this paper utilizes the distance between the image and camera. Sensor fusion is then performed to obtain a wide bandwidth sensing of the micro angular motions. Experiments are performed and the results demonstrate that the proposed algorithm can estimate the displacement of frequencies from low to high with high resolution.